INFORMATION about an underground plant which produced tainted bean sprouts in Qingpu District earned a 50,000 yuan (US$7,937) reward for an anonymous informant in February, the largest sum paid for a food scandal tip-off in the city so far, Shanghai Food Safety Office said yesterday.

The authority is keen to have the public help them uncover food safety issues and anonymity will be protected and, indeed, encouraged, officials said at the launch of a national food safety week.

"Industry insiders and informants can usually give valuable information, but they are afraid that their identities will be exposed," said Gu Zhenhua, vice director of the food safety office. "So we encourage anonymous tipsters. In the bean sprout case, we don't know the tipster's identity. After confirming all the information the person offered, the 50,000 yuan was transferred to an account designated by the person.

All the contaminated bean sprouts have been destroyed and suspects are under investigation by the Qingpu prosecutors' office.

Shanghai is offering rewards of between 500 and 200,000 yuan for food scandal tip-offs.

Officials said ensuring food safety was a tough task in the city and the government was using all measures to deal with food safety cases to protect people's health. Any food safety crime would receive the toughest punishment, the government has said.

At present, about 80 percent of local food producers are small companies, making monitoring and supervision difficult. There are about 180,000 to 200,000 food production or sales companies in the city, but only 4,000 food safety officials.

"We want all residents to participate in the campaign against food safety crime for the sake of public health," Gu said.